Word: nasa
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Dates: during 1990-1999
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Just getting Pathfinder from Cape Canaveral to Ares Vallis required a remarkable bit of cosmic sharpshooting. Mars is only 4,200 miles across--about half as big as Earth--and the floodplain NASA was aiming for is only 60 miles wide. The barest flutter in the spacecraft's trajectory could have caused Pathfinder to swing far wide of its destination. To prevent the ship from straying too far from its ideal path, the flight plan included five different opportunities for midcourse corrections during which the spacecraft's thrusters could be fired to refine the trajectory. Over the course...
Nonetheless, when Pathfinder actually reached the upper limits of Mars' wispy atmosphere, it would still have been possible for NASA to put the ship into the rough. The 1,256-lb. polyhedron-shaped pod was screaming toward the planet at 16,600 m.p.h., a speed that caused it to experience deceleration forces nearly 20 times as great as than Earth's gravity. In order to survive, the spaceship had to approach the planet at an angle of about 14.2[degrees]. "Go in too steep and you could crash and burn," says Pathfinder project scientist Matthew Golombek. "Go in too shallow...
Happily, this was a problem NASA had foreseen. In J.P.L.'s so-called sandbox, a roomful of Mars-like rock and soil with a mock-up lander and rover, the engineers had rehearsed a fairly straightforward maneuver that called for Pathfinder to raise one petal, tilting the entire craft 45[degrees], retract the deflated bag further and then lower the petal. The signal to execute the maneuver was sent up shortly before Earth set over the Martian horizon, breaking the communications link until dawn; just before the connection was actually severed, a picture came back confirming that the command...
...degrees]F at night) at last claim it. The Pathfinder lander, with instruments and cameras of its own, could function for as little as a month or as long as a year. Even after it winks out, it will continue to serve an important symbolic function. On Saturday NASA announced that it would rename the spent lander the Carl Sagan Memorial Station...
What was perhaps most remarkable about the spacecraft that set up shop in Ares Vallis late last week is how unremarkable they are. NASA's early interplanetary spacecraft--the Vikings, the Pioneers, the Voyagers--were limousine ships packed with dozens of scientific instruments and countless backup systems. On the surface, of course, this made sense. "If you've never been to Jupiter or Saturn before," says Golombek, "you want a whole bunch of instruments to cover the sphere of what you want to know...